Data storage libraries are known for providing cost effective on-line access to large quantities of data. Typically, data storage libraries include a large number of data storage shelves on which are stored data storage media. The typical data storage media is a tape cartridge or an optical cartridge. A robot accessor typically accesses the data storage media from the data storage shelves and delivers the accessed media to a data storage drive for reading and/or writing data on the accessed media. Suitable electronics both operate the robot accessor and operate the data storage drives to transmit and/or receive data from an attached on-line host computer system.
In a conventional data storage library, the data storage shelves are arranged in a planar orthogonal arrangement forming a "wall" of data storage media. The plane may be a flat plane, or may be a cylindrical plane. To double the storage capacity, two "walls" of data storage media may be provided on either side of the robot accessor.
The robot accessor is therefore arranged to move in the two orthogonal directions to access date storage media along the "wall" of data storage media stored in the data storage shelves. With two "walls" of data storage media, the robot accessor is additionally arranged to move in a third direction to access either of the two "walls" of data storage media.
To maintain the data storage media in the data storage shelves without risk of displacement, the shelves in some data storage libraries are tilted at an inclined angle towards, or a downwardly inclined angle away from, the robot accessor. The inclined angle (which is about 10-15 degrees) prevents cartridge fall out due to earthquakes. The robot accessor is designed to access the data storage media from the data storage shelves at the downwardly inclined angle and to insert the accessed data storage media into the data storage drive at the same downwardly inclined angle. The data storage drive conventionally has a pivoting loader to accept the inserted data storage media at the downwardly inclined angle and then pivot downward to a level position, loading the data storage media in the read/write drive mechanism.
The quantity of data stored in the data storage library is a function of the number of data storage media stored in the library shelves and the data capacity of each data storage media. To increase the data capacity of the media, it would be advantageous to employ data storage drives having the ability to write data on the cartridges at high capacities. Some tape drives with the highest capacities have high precision horizontal insertion (or X-Y) loaders for receiving data storage media. Upon receiving the data storage media horizontally (X), the loaders move downward (Y) to precisely load the data storage media in the read/write drive mechanism, similar to conventional VCR loaders.
The high capacity horizontal insertion loader data storage drives may therefore not be compatible with a data storage library having downwardly inclined shelves.
A potential solution would be to utilize a robot accessor with an additional degree of motion for changing the angle of the robot accessor from that of a downward inclination for the shelves to a horizontal direction for the data storage drives. However, the cost of providing such a robot accessor is inconsistent with the cost effective access to data provided by existing data storage libraries. In addition, the use of horizontal shelves would not retain the data storage media during ground disturbances unless a costly latching mechanism were provided for each shelf.